Red Orchestra 2: Heroes of Stalingrad will allow the change from scope to iron sights as shown here @ 3:40.



The game is not out yet, though.

Red Orchestra is an amazing game - by far the most realistic shooter I've ever encountered. It ruined the COD/MOH/Battlefield series for me permanently. I play Red Orchestra: Darkest Hour (a Western Front mod for the original) almost every day now, and new maps are always coming online. It was by far the best $15 I've ever spent on a game.

Tripwire is a really good developer and I have very high hopes for Heroes.